Progresses on our understanding the processes of star formation in the Milky Way from Herschel observations Davide Elia INAF-IAPS, Roma Part II The Herschel.

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Presentation on theme: "Progresses on our understanding the processes of star formation in the Milky Way from Herschel observations Davide Elia INAF-IAPS, Roma Part II The Herschel."— Presentation transcript:

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Progresses on our understanding the processes of star formation in the Milky Way from Herschel observations Davide Elia INAF-IAPS, Roma Part II The Herschel photometric surveys

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Herschel and star formation The wavelength range covered by the cameras on board Herschel contains the emission peak of the cold dust. It is suited for studying the dense clouds and the early stages of star formation!

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Nature of the compact sources Warm Cores SED sources are under-luminous with respect to UCHII/HotCores of similar envelope mass Concurring indications suggesting that the dominant source in the Warm Core objects is not yet on the ZAMS ZAMS ACCRETION Molinari et al. 2008 Hot Core Warm Core In a pre-Herschel SED analysis of sample of 42 intermediate and high- mass star forming region from the sample of Molinari et al. (1996), a Class 0-I-II sequence analogous to the low-mass regime was suggested: Warm Cores to Hot Cores to HII-driving objects

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Aquila rift and Polaris flare André et al. 2010, A&A, 518, L102; Könives et al. 2010, A&A, 518, L106 Prestellar cores are only observed above the threshold A V = 7 because they form out of a filamentary background and only the supercritical, gravitationally unstable filaments are able to fragment into bound cores.

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The two sources are situated a few 10^3 AU apart, corresponding to a few Jeans lengths. It is then possible that these two sources formed at almost the same time from the fragmentation of a larger structure. Two First Hydrostatic Cores in Perseus Pezzuto et al. 2012, A&A, 547, A54 envelope: T = 9 K, M = 7.3 M ʘ envelope: T = 9.4 K, M = 8 M ʘ

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O-stars from NGC 2244 Filaments in the Rosette molecular cloud “Confidence map” highligthing the filament junctions Existing infrared clusters and the most massive dense cores (potential sites of future massive star formation) identified in the same data set are overlaid on the image. All sources lie in the proximity of junctions Schneider et al. 2012, A&A 540, L11

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Vela–C - Compact source extraction Sources are searched separately on each map CuTEx: sources detected as local maxima in the curvature map (2nd derivative) An elliptical Gaussian is fitted on them, and geometric parameters estimated A list of sources with S/N>5 is obtained at each λ

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Vela–C - An evolutionary framework Class 0 Although not completely separated, the pre- and proto-stellar core samples show a global trend to populate different regions of the diagram. For proto-stellar cores, L bol is probably underestimated, resulting in an underestimate of their actual age. Giannini et al. 2012, A&A 539, A156